Rotary engine cooling system

ABSTRACT

There is disclosed a rotary engine cooling system that passes the coolant from a coolant pump through an intermediate heat region of the engine, the hotest heat region of the engine, a heater, the coolest region of the engine and the pump inlet in that order while coolant is also directed through an internal bypass to the pump inlet in parallel with coolant flow to the heater. When the engine has sufficiently warmed up the system passes the coolant through the intermediate heat region, the hot region and then to a radiator before returning to the pump inlet while coolant continues to flow through the heater and the coolest region of the engine to the pump inlet.

United States Patent [191 Green et al.

[451 Sept. 23, 1975 ROTARY ENGINE COOLING SYSTEM [73] Assignee: General Motors Corporation,

Detroit, Mich.

22 Filed: May 22,1974

21 Appl. No.: 472,429

COOLANT PUMP LOCATION 3,743,452 7/l973 Steinwart 418/84 Primary Examiner-C. .l. Husar Assistant ExaminerLeonard Smith Attorney, Agent, or FirmRonald L. Phillips [5 7 ABSTRACT There is disclosed a rotary engine cooling system that passes the coolant from a coolant pump through an intermediate heat region of the engine, the hotest heat region of the engine, a heater, the coolest region of the engine and the pump inlet in that order while coolant is also directed through an internal bypass to the pump inlet in parallel with coolant flow to the heater. When the engine has sufficiently warmed up the sys tem passes the coolant through the intermediate heat region, the hot region and then to a radiator before returning to the pump inlet while coolant continues to flow through the heater and the coolest region of the engine to the pump inlet.

3 Claims, 4 Drawing Figures US Patent Sept. 23,1975 Sheet 1 of 3 3,907,468

ROTARY ENGINE COOLING SYSTEM This invention relates to rotary engine cooling systems and more particularly to the coolant distribution therein.

In rotary engines, the cooling requirements are substantially greater than those in reciprocating piston engines and because of its comparatively small size and the desire to maintain its outer envelope small, the usual engineering and manufacturing approaches are not generally suitable to providng the most efficient cooling system possible in a rotary engine. For example, it was believed by some skilled in the rotary engine art that for best use of a multi-pass series connected axial flow arrangement to bolster its advantages over a peripheral flow arrangement, the coolant from the radiator should first be passed through the engines hotest region. But this normally necessitates mounting the coolant pump at a mid-heighth engine location which is undesirable from the standpoint of connection to the radiators outlet and also accessibility recognizing that a low mounted coolant pump could have a direct connection with the radiator outlet and better accessibility. We have found that by controlling the coolant distribution and velocity in a certain different manner the cooling can be optimized while permitting the coolant pump to be located in a very convenient location low in one of the engines end housings with a short connection to the radiator outlet. In our arrangement, the coolant is first passed through the engines intermediate heat region at a slow rate and then through the hotest region at a fast rate. Furthermore, in our cooling system arrangement we employ a special thermostatically controlled valve to block coolant flow to the radiator to effect fast engine warm up and permit flow to the radiator after the engine is warmed up while all the time passing coolant from the engines hotest region through an external passenger space heater and then to the engines coolest region but bypassing some flow past the heater when flow to the radiator is blocked during engine warm up to prevent excessive pressures in the' heater. As a result, our arrangement enables a very suitable pump location and provides optimum heat transfer operation with a cold engine and also after the engine is warmed up while fully serving the needs of the heater and preventing excessive pressures therein without separate valving.

An object of the present invention is to provide a new and improved rotary engine cooling system.

Another object is to provide a rotary engine cooling system that for cold engine operation directs coolant first through the engines intermediate heat region, then the engines hotest region and then through a passenger space heater to the engines coolest region whereafter it is recirculated and on engine warm up directs coolant from the hotest region to a radiator and back to the intermediate heat region while continuing to direct coolant through the heater and the coolest region.

Another object is to provide a rotary engine cooling system that for cold engine operation directs coolant first through the engines intermediate heat region, then the engines hotest region and then through a passenger space heater to the engines coolest region whereafter it is recirculated while some coolant is bypassed past the heater to the intermediate heat region and on engine warm up directs coolant from the hotest region to a radiator and back to the intermediate heat region while continuing to direct coolant through the heater and the coolest region.

These and other objects of the present invention will be more apparent from the following description and drawing in which:

FIG. 1 is a longitudinal view with parts in section of a rotary combustion engine having a cooling system according to the present invention.

FIG. 2 is an enlarged view taken along the line 22 in FIG. 1.

FIG. 3 is an enlarged view with parts in section and parts broken away of the cooling systems thermostatically controlled valve assembly.

FIG. 4 is an exploded view of certain of the engine parts and also a diagrammatic view of the other cooling system parts.

Referring to FIGS. 1, 2, and 4, there is shown a tworotor rotary engine 10 having a cooling system according to the present invention. The engine 10 has an outer body comprising a front end housing 14, a rear end housing 16, a front rotor housing 17, a rear rotor housing 18, and an intermediate housing 19 between the two rotor housings 17 and 18, all clamped together by bolts 20. The engine housing encloses a pair of chambers 22 and 23 that are defined respectively by inwardly facing peripheral walls 24 and 26 of rotor housings 17and l8 and opposed, spaced parallel end walls 28, 30 and 32, 34 of the housing 14 and intermediate housing 19 and the latter housing and other housing 16. Each of the peripheral walls 24 and 26 is in the shape of a two-lobe epitrochoid 0r curve parallel thereto whose center line is indicated at 36. A crankshaft 42 extends through the chambers 22 and 23 and is rotatably supported in main sleeve bearings 44 and 45 which are fixed in stationary gears 46 and 47 that are bolted to the respective housings l4 and 16 as shown in FIG. 1, the crankshafts axis being coincident with the center line 36 which is parallel to the peripheral walls 24 and 26.

The crankshaft 42 is provided in the housing chambers 22 and 23 with eccentrics 50 and 52 on which hollow rotors 54 and 56 with sleeve bearings are mounted for rotation about the eccentric centers 59 and 60, these centers being located apart and spaced equal distances from the crankshaft axis 36. The rotors 54 and 56 have the same general shape of a triangle having respectively three faces 61 and 62 which are convex and face the peripheral walls 24 and 26 and cooperate therewith and with the end walls 28, 30 and 32, 34 to define three variable volume working chambers 67 and 68 that are spaced about the rotors and move with the rotors within the engine housing.

A fixed cyclic relation between each of the rotors and the crankshaft is obtained by gearing between each of the rotors and the housing. Referring to rotor 54, there is the stationary gear 46 which is fixed to the housing and is received about and is concentric with the crankshaft 42. The gear 46 meshes with an internal tooth gear 71 that is concentric with and formed on the outboard side of rotor 54. The gear 71 has 1V2 times the number of teeth as the gear 46 with result that this gearing enforces a fixed cyclic relation such that the crankshaft makes three complete revolutions for every one complete revolution of the rotor. Similarly, the other stationary gear 47 meshes with an internal tooth gear 73 on the other rotor 56 with their mesh at a location diametrically opposite that of gears 46 and 71.

Thus, the chambers 67 and 68 move with the respective rotors 54 and 56 as they revolve about their axes while also revolving about the crankshaft axis with each chamber twice undergoing expansion and contraction during each rotor revolution.

Sealing of the working chambers such as the working chambers 67 is effected by three apex seals 74 each of which extends the width of the rotor and is mounted in an axially extending slot at one of the rotor apexes, six corner seals 75 each of which is mounted in a hole in one of the rotor sides near one of the rotor apexes, and twelve side seals 76 each of which is mounted in an arcuate groove in one of the rotor sides with these seals arranged in pairs and extending adjacent one of the rotor faces between two of the corner seals with the corner seals each providing a sealing link between one apex seal and the adjacent ends of two pairs of side seals. The apex seals 74 are each spring biased radially outward to continuously engage the peripheral wall 24 and both the corner seals 75 and the side seals 76 in both rotor sides are spring biased axially outward to continuously engage the respective end walls 28 and 30. In addition, there is mounted in grooves in each rotor side inward of the side seals 76 a pair of spring biased circular oil seals 82 which are concentric with the rotor and sealingly engage the opposite end wall to prevent oil from reaching further outward. The rotor 56 carries a similar gas and oil seal arrangement.

A combustible air-fuel mixture is delivered by an induction system, not shown, that includes a carburetor that is mounted on an intake manifold. The intake manifold is connected to the engine housing and has branches that communicate in the engine housing with intake ports 84 and 86 in the respective housing end walls as shown in the end walls and 34 in FIG. 4. Upon rotor rotation the combustible air-fuel mixture is sequentially, periodically admitted to the chambers 67 and 68 as they are expanding by the traversing motion of the rotor sides relative to the respective intake ports whereafter the chambers then close to their intake ports and contract to compress the thus trapped airfuel mixture in readiness for ignition. Combustion by spark ignition is provided by a suitable ignition system, not shown, which applies voltage at the proper time to pairs of spark plugs 88 and 89 which are mounted on the rotor housings, as shown in FIG. 4, with their electrodes open to the combustion chambers through the respective peripheral walls. Fow example, the electrodes of the two spark plugs 88 mounted on rotor housing 17 are open to the chambers 67 through the interior peripheral wall 24 and are peripherally spaced thereabout so that one plug leads the other plug relative to rotor rotation. In such an arrangement both plugs are tired at the same time or different times or only one plug is fired according to certain engine operating conditions as is well known. With combustion the peripheral wall takes the reaction to force the rotor to continue rotating and eventually each working chamber following the power phase is exhausted during the exhaust phase by an exhaust port 92 in the peripheral wall 24 that is periodically traversed by the rotor apexes and is open to an exhaust manifold, not shown, secured to the exterior of the engine housing. The engine structure thus far described is of conventional type and for a more detailed understanding thereof reference may be made to U.S. Pat. Nos. 2,988,065 and Describing now the engines lubrication system and deferring the details of the coolant system until last, oil is drawn by an oil pump 95 from an oil tank 96 secured to the bottom of the engine. The oil is drawn up a suction hole 102 in the bottom of the rear housing 16 through a screen 103 and suction pipe 104 and thereafter passes forwardly to the front housing 14 where the oil pump is mounted via a horizontal passage 105 formed in the housings l6, 18, 19, 17 and 14 as shown in FIG. 4. The oil pump 95 is of the internal-external gear type and is mounted about and is driven by the crankshaft 42 as best shown in FIG. 1. Oil pump 95 delivers the oil under pressure to an external cooler, not shown, from which the oil is then directed to a passage 106 in the rear housing shown in FIG. 4. Passage 106 delivers the oil to an oil filter, not shown, that is mounted on a pad 108 on the rear housing and from the filter, oil is delivered to a distribution passage 110 with the pressure feed to the cooler and also the distribution pressure in the engine controlled by suitable pressure regulator valves, not shown, such as disclosed in copending U.S. patent application Ser. No. 432,848, filed Jan. 14, 1974 and assigned to the assignee of this invention. The pressure distribution passage 110 runs into an oil gallery tube 112, shown in FIG. 1, that passes through a passage in the rotor housings l7 and 18 and intermediate housing 19. Tube 112 joins at its opposite ends in the front and rear housings 14 and 16 with long drilled holes 114 and 116, respectively, that run from the gallery toward the center of the housings and stationary gears 46 and 47. The oil gallery tube 112 is a slip fit in the front and rear housings l4 and 16 so that oil passes through the tube and does not have to cross the several gasketed joints of the engine. Oil is forced into the crankshaft at each end through holes in the front and rear stationary gears 46 and 47, radial holes in the front and rear main bearings 44 and 46 and radial holes in the crankshaft 42 to a long axial feed hole in the crankshaft that is drilled from the rear end thereof and is plugged by a press-fitted ball 13]. Thus, the main bearings are fed with oil for lubrication and, in addition, radial holes connect the axial feed passage 130 to feed oil to the rotor bearings for their lubrication. In addition, radial holes connected to the axial feed passage 130 either side of the eccentrics direct oil radially outwardly to lubricate the phase gears and also to pass into the interior of the respective rotors 54 and 56 to effect their cooling. The rotors each have an internal web with holes 132 to provide for circulation therethrough in an axial direction with the oil then exiting outwardly of the rotor and into cavities 146 and 148 in the front and intermediate housings 14 and 19 in the case of rotor 54 and into the intermediate cavity 148 and a cavity 150 in the rear housing 16 in the case of rotor 56. Oil in the pressurized distribution passage 110 is also delivered to an oil metering pump, not shown, which meters oil at a suitable rate to lubricate the rotors gas seals. This oil metering pump may be of the type disclosed in copending U.S. application Ser. No. 357,072, filed May 3, 1973 now U.S. Pat. No. 3,84l,803, and assigned to the assignee of this invention and may be connected to meter oil to mix with the fuel in the carburetor or to oil feed ports in the housing end walls.

The oil after leaving the main bearings, rotor bearings, phase gears and rotor cavities, falls through the cavities 146, 148 and 150 to a horizontal drain passage 158 that extends through the housings as shown in FIG. 4. The oil then drains to the oil tank 12 through a drainvent hole 160 in the rear housing 16 as best shown in FIG. 4. Air is vented internally in the engine by a continuous air flow which is effected by the provision of a breather passage 162 in the front housing 14 which is connected by a hose, not shown, to pull air from the engines air cleaner and the provision of an air-oil separator, not shown, which is mounted on the rear housing 16 and is connected by a hose and the usual PCV valve, not shown, whereby air is pulled from a top cavity 170 in the rear housing to the carburetor while separating out and draining oil to the drain cavity 150. In this air flow system there are three parallel air paths through the housings, namely the drain passage 158 which carries air along with the oil from the front housing to the oil tank, upper vent passages 172 that can carry air from either the front housing breather cavity 162 to the rear housing vent cavity 170 or in the reverse direction to compensate for the air carried from the oil drain passage and a third passage which is through the hollow rotors. In addition, the upper vent passage, the rotor vent passage and the drain passage are connected in the front, intermediate and rear housings for cross-flow and pressure equilization as shown in FIGS. 1 and 4.

In the rotary engine structure described above the housing temperature varies about the central axis thereof and can be divided into three distinct heat regions or zones as shown in FIG. 2 wherein the coolest heat region 180 encompasses the intake port location, the hotest heat region 182 encompasses the spark plug locations and the intermediate heat region 184 encompasses the exhaust port location, the latter region being referred to as an intermediate heat region since it experiences temperatures intermediate or between those of the coolest and hotest regions. In the cooling system according to the present invention, coolant is first directed through the intermediate heat region 184 and then the hotest region 182 and is then directed through either the coolest region 180 or is first externally cooled and then directed through the coolest region.

The cooling system comprises a coolant pump 186 which is mounted very low in the front end housing 14 as shown in FIG. 1 with the housing accommodation for the pump projecting lower than any other portion thereof. The coolant pump 186 is driven by a belt and pulley arrangement 188 from the front end of the crankshaft 42 and is of the centrifugal type having an impeller 190 which draws coolant from the pumps inlet 192 formed in the front end housing 14 and discharges the coolant to a pump outlet 194 also formed in the front end housing as shown in FIG. 4. As shown in FIGS. 2 and 4, the engines housings 14, 16, 17, 18 and 19 have formed therein a multi-pass series connected axial flow arrangement comprising a plurality of first pass coolant passages 196 arranged throughout the engine's intermediate heat region 184, a plurality of second pass coolant passages 198 arranged throughout the engines hotest region 182 and a plurality of bypass coolant passages 200 arranged throughout the engines coolest region 180. Furthermore, the second pass coolant passages 198 are determined to have a smaller net effective flow area than that of the first pass coolant passages 196 for reasons which will become more apparent later.

In the front end housing 14 the first pass coolant passages 196 have a manifold 202 which is connected to the coolant pumps outlet 194 and proceed therefrom longitudinally or axially of the engine through the front rotor housing 17 to a manifold 204 in the intermediate housing and then axially through the rear rotor housing 18 to the lower region of a manifold 206 in the rear end housing 16. The manifold 206 in its upper region is connected to the second pass passages 198 which proceed axially through the rear rotor housing 18 and are joined in the intermediate housing 19 by a manifold 208 and then proceed axially through the front rotor housing 17 to a manifold 210 that is in turn connected to a distribution manifold 219 in the uppermost coolest region of the front end housing 14. The bypass coolant passages 200 have an external inlet 212 that is directly connected to a manifold 214 in the rear end housing 16 and then proceed axially through the rear rotor housing 18 to a manifold 216 in the intermediate housing 19 and then through the front rotor housing 17 to a manifold 218 at a mid-heighth location in the front end housing 14 that is connected to the pump inlet 192. As shown in FIG. 4, all of the above described manifolds extend both radially and angularly in the housings to pass the coolant over large surface areas adjacent the working chamber walls for efficient cooling. In addition, there is provided in the front end housing 14 as best shown in FIG. 3 a heater bypass passage 220 that is connected at one end to the distribution manifold 219 and is open at the other end to one of the bypass coolant passages 200 in the front rotor housing 17 and is thus connected by the bypass passageway and then the bypass manifold 218 in the front end housing to the pump inlet 192 for reasons which will become more apparent later.

As shown in FIG. 4, the cooling system further includes an external radiator 222 having an outlet at its bottom tank connected by a hose 224 to the pump inlet 192 and an inlet at its upper tank connected by a hose 226 to a passage 228 at the top of the front end housing 14 that is connected to the distribution manifold 219. In addition, there is a passenger space or car heater 230 having an inlet which is connected by a hose 232 to the distribution manifold 219 in the front end housing 14, this connection being made through an orifice 233 in a nipple 234 which is threaded in the rear face of the front end housing in the passage 236 from this manifold as shown in FIG. 3. The heater 230 has an outlet which is connected by a hose 238 to the inlet 212 to the bypass manifold 214 in the rear end housing 16 as shown in FIG. 4.

The distribution of coolant to the radiator 222 and the bypass passages 200 is controlled by a single thermostatically controlled valve assembly 240 which is mounted in the front end housing 14 as shown in FIG. 3. This valve assembly has the usual thermostatic element 242 but operates two valves 244 and 246 instead of the normal single valve to provide the desired coolant distribution. When the coolant is below a predetermined temperature, i.e., when the engine is cold, the valve assembly is positioned as shown with the valve 244 blocking flow from the distribution manifold 219 to the radiator delivery passage 228 and thus to the radiator 222 while the other valve 246 which is fixed to move therewith is in a position opening the distribution manifold 219 to the bypass delivery passage 220. Alternatively, when the predetermined coolant temperature is exceeded, i.e., the engine is sufficiently warm, the valve assembly 240 operates to position the valve 244 so that the distribution manifold 219 is open to the radiator delivery passage 228 while the other valve 246 is positioned to either fully or partially block coolant flow from the distribution manifold 219 to the bypass passage 220 as shown by the phantom line valve positions.

Describing now the cooling system operation provided by our arrangement, coolant enters the rotary engine 10 from the radiator 222 and passes through the pump inlet 192 to the coolant pump 186 by which it is then delivered under pressure through the pump outlet 194 to the manifold 202 in the front end housing 14. At the manifold 202 the coolant in the first pass is distributed amongst the first pass coolant passages 196 to move axially along the engine with some of the coolant moving over the exhaust ports as it progresses along the engine and some of the coolant moving along the engine just below the ignition area of the working chambers and these coolant streams all coming together in the rear end housing 16 in the manifold 206 with the coolant that passed over the exhaust ports moving downwards on either side of the exhaust port in the rear rotor housing 18 in order to reach the manifold 206 in the rear end housing. To prevent air or steam from collecting to the first pass coolant passages past the exhaust ports, there is provided a small bleed passage 248 in the rear end housing 16 to allow vapor to escape from the first pass into the above bypass manifold 214.

Coolant in the manifold 206 then moves upward into the second pass coolant passages 198 where is passes axially along the engine past the spark plugs and into the manifold 210 in the front end housing 14 and then into the distribution manifold 219 in the upper region of this housing. Thus, the flow rate through the first and second coolant passages is the same since they are actually connected in series. However, the flow through the second pass in the hotest region is faster than through the first pass because of its smaller net effective flow area and is thus better able to handle the greater heat flux in this area.

With a cold engine, the thermostatically controlled valve assembly 240 is conditioned as shown with valve 244 closed so that coolant in the distribution manifold 219 is thus blocked from flowing to the radiator 222. A small portion of the coolant delivered to the distribution manifold 219 is permitted by the orifice 233 to flow through the heater 230 to the manifold 214 of the bypass coolant passages 200 in the rear end housing 16. The coolant moves axially along the engine through these passages and also moves downwards in the bypass region of the rotor housings at four places which are at either side of the ribs 249 and 250 in the respective rotor housings l7 and 18. This allows the coolant to reach the mid-heighth location of the manifold 218 in the front end housing 14 which is connected to the pump inlet 192. In parallel with this flow, the remaining major or large portion of coolant delivered to the distribution manifold 219 is permitted by the open valve 246 to pass through the heater bypass passage 220 into the front rotor housing 17 where it can then proceed past the front rotor housing rib 249 in the bypass coolant passageway to the manifold 218 and enter the suction side of the pump 186 to thereby prevent excessive pressures from building up in the heater 230.

When the engine has warmed sufficiently, the thermostatically controlled valve assembly 240 operates so that the valve 244 opens to permit flow from the distribution manifold 219 to the radiator while the other valve 246 closes to block flow from the distribution manifold to the heater bypass passages 220. As a result, the flow through the heater 230 is not affected by the operation of the thermostat but the large amount of coolant flow that was being bypassed past the heater to limit the pressure therein is now blocked since it was found that excessive pressures in the heater will not be encountered with the flow to the radiator. In the particular arrangement shown the valve 246 in its closed position does allow some leakage; however, it will be appreciated that this valve could be of a positive closing type to prevent any leakage.

The above described embodiment is illustrative of the invention which may be modified within the scope of the appended claims.

We claim:

1. A rotary combustion engine having at least one rotor housing and a pair of end housings, a coolant pump having an inlet and an outlet in one of said end housings, said housings having a first pass coolant passage connected to said pump inlet in said one end housing and extending axially through said rotor housing in an intermediate heat region thereof where working chamber exhaust occurs and terminating in the other of said end housings, said housings further having a second pass coolant passage connected to said first pass coolant passage in said other end housing and extending axially through said rotor housing in the hotest heat region thereof where working chamber combustion occurs and terminating in said one end housing, said housings further having a bypass coolant passage originating at one end in said other end housing and extending axially through said rotor housing in the coolest region thereof where working chamber intake occurs and connected at the opposite end to said pump inlet in said one end housing, a radiator having an inlet connected to said second pass coolant passage at said one end housing and having an outlet connected to said pump inlet at said one end housing, a heater having an inlet connected to said second pass coolant passage at said one end housing and having an outlet connected to said bypass coolant passage at said other end housing, said one end housing and said rotor housing having a heater bypass passage connected at one end in said one end housing to said second pass coolant passage and connected at the opposite end to said bypass coolant passage in said rotor housing and thus to said pump inlet in said one end housing, and thermostatically controlled valve means in said one end housing for blocking coolant flow to said radiator and permitting fluid flow to said heater bypass passage below a predeter mined coolant temperature and, alternatively, permitting coolant flow to said radiator and limiting flow to saidheater bypass passage above said predetermined temperature whereby when the engine is cool, coolant passes through said first pass coolant passage and then said second pass coolant passage and then said heater and then said bypass coolant passage to said pump inlet while coolant is also permitted to pass through said heater bypass passage to said pump inlet in parallel with coolant flow to said heater to prevent excessive pressures in said heater and when the engine has sufficiently warmed up, coolant passes first through said first pass coolant passage and then said second pass coolant passage and then said radiator to said pump inlet while coolant continues to flow through said heater and then through said bypass coolant passage to said pump inlet.

2. A rotary combustion engine having a rotor housing with a spark plug and an exhaust port and a pair of end housings with intake ports, a coolant pump having an inlet and an outlet in one of said end housings, said housings having first pass coolant passage means connected to said pump inlet in said one end housing and extending axially through said rotor housing around said exhaust port and terminating in the other of said end housings, said housings further having a second pass coolant passage connected to said first pass coolant passage in said other end housing and extending axially through said rotor housing around said spark plug and terminating in said one end housing, said housings further having a bypass coolant passage originating at one end in said other end housing and extending axially through said rotor housing and around said intake ports in said end housings and connected at the opposite end to said pump inlet in said one end housing, a radiator having an inlet connected to said second pass coolant passage at said one end housing and having an outlet connected to said pump inlet at said one end housing, a heater having an inlet connected to said second pass coolant passage at said one end housing and having an outlet connected to said bypass coolant passage at said other end housing, said one end housing and said rotor housing having a heater bypass passage connected at one end in said one end housing to said second pass coolant passage and connected at the opposite end to said bypass coolant passage in said rotor housing and thus to said pump inlet in said one end housing, and thermostatically controlled valve means in said one end housing for blocking coolant flow to said radiator and permitting fluid flow to said heater bypass passage below a predetermined coolant temperature and, alternatively, permitting coolant flow to said radiator and blocking flow to said heater bypass passage above said predetermined temperature whereby when the engine is cool, coolant passes through said first pass coolant passage and then said second pass coolant passage and then said heater and then said bypass coolant passage to said pump inlet while coolant is also permitted to pass through said heater bypass passage to said pump inlet in parallel with coolant flow to said heater to prevent excessive pressures in said heater and when the engine has sufficiently warmed up, coolant passes first through said first pass coolant passage and then said second pass coolant passage and then said radiator to said pump inlet while coolant continues to flow through said heater and then through said bypass coolant passage to said pump inlet.

3. A rotary combustion engine having a pair of end housings, a pair of rotor housings between said end housings and an intermediate housing between said rotor housings, a coolant pump having an inlet and an outlet in one of said end housings, said housings having first pass coolant passage means connected to said pump inlet in said one end housing and extending axially in a plurality of branches through said rotor housings and said intermediate housing in an intermediate heat region thereof where working chamber exhaust occurs and terminating in the other of said end housings, said housings further having second pass coolant passage means connected to said first pass coolant passage means in said other end housing and extending axially in a plurality of branches through said rotor housings and said intermediate housing in the hotest heat region thereof where working chamber combustion occurs and terminating in said one end housing, said housings further having bypass coolant passage means originating at one end in said other end housing and extending axially in a plurality of branches through said rotor housings and said intermediate housing in the coolest region thereof where working chamber intake occurs and connected at the opposite end to said pump inlet in said one end housing, a radiator having an inlet connected to said second pass coolant passage means at said one end housing and having an outlet connected to said pump inlet at said one end housing, a heater having an inlet connected to said second pass coolant passage means at said one end housing and having an outlet connected to said bypass coolant passage means at said other end housing, said one end housing and the one rotor housing closest to said one end housing having heater bypass passage means connected at one end in said one end housing to said second pass coolant passage means and connected at the opposite end to said bypass coolant passage means in said one rotor housing and thus to said pump inlet in said one end housing, a bleed passage connecting said first pass coolant passage means to said bypass coolant passage means in said other end housing, and thermostatically controlled valve means in said one end housing for blocking coolant flow to said radiator and permitting fluid flow to said heater bypass passage means below a predetermined coolant temperature and, alternatively, permitting coolant flow to said radiator and blocking flow to said heater bypass passage means above said predetermined temperature whereby when the engine is cool, coolant passes through said first pass coolant passage means and then said second pass coolant passage means and then said heater and then said bypass coolant passage means to said pump inlet while coolant is also permitted to pass through said heater bypass passage means to said pump inlet in parallel with coolant flow to said heater to prevent excessive pressures in said heater and when the engine has sufficiently warmed up, coolant passes first through said first pass coolant passage means and then said second pass coolant passage means and then said radiator to said pump inlet while coolant continues to flow through said heater and then through said bypass coolant passage means to said pump inlet.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,907,468

DATED September. 23, 1975 INVENTOR( I Raymond J. Green, Erkki A. Koivunen It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: 7

Column 4; line 37; the numeral "46" should reed Column 7, line 25, "to" should read line 30, 'is" should read.-- it Signed. and Sealed this [SEAL] twenty'ni'lth D y f June1976 A ttest:

RUTH C. MASON Commissioner ofPalents and Trademarks 

1. A rotary combustion engine having at least one rotor housing and a pair of end housings, a coolant pump having an inlet and an outlet in one of said end housings, said housings having a first pass coolant passage connected to said pump inlet in said one end housing and extending axially through said rotor housing in an intermediate heat region thereof where working chamber exhaust occurs and terminating in the other of said end housings, said housings further having a second pass coolant passage connected to said first pass coolant passage in said other end housing and extending axially through said rotor housing in the hotest heat region thereof where working chamber combustion occurs and terminating in said one end housing, said housings further having a bypass coolant passage originating at one end in said other end housing and extending axially through said rotor housing in the coolest region thereof where working chamber intake occurs and connected at the opposite end to said pump inlet in said one end housing, a radiator having an inlet connected to said second pass coolant passage at said one end housing and having an outlet connected to said pump inlet at Said one end housing, a heater having an inlet connected to said second pass coolant passage at said one end housing and having an outlet connected to said bypass coolant passage at said other end housing, said one end housing and said rotor housing having a heater bypass passage connected at one end in said one end housing to said second pass coolant passage and connected at the opposite end to said bypass coolant passage in said rotor housing and thus to said pump inlet in said one end housing, and thermostatically controlled valve means in said one end housing for blocking coolant flow to said radiator and permitting fluid flow to said heater bypass passage below a predetermined coolant temperature and, alternatively, permitting coolant flow to said radiator and limiting flow to said heater bypass passage above said predetermined temperature whereby when the engine is cool, coolant passes through said first pass coolant passage and then said second pass coolant passage and then said heater and then said bypass coolant passage to said pump inlet while coolant is also permitted to pass through said heater bypass passage to said pump inlet in parallel with coolant flow to said heater to prevent excessive pressures in said heater and when the engine has sufficiently warmed up, coolant passes first through said first pass coolant passage and then said second pass coolant passage and then said radiator to said pump inlet while coolant continues to flow through said heater and then through said bypass coolant passage to said pump inlet.
 2. A rotary combustion engine having a rotor housing with a spark plug and an exhaust port and a pair of end housings with intake ports, a coolant pump having an inlet and an outlet in one of said end housings, said housings having first pass coolant passage means connected to said pump inlet in said one end housing and extending axially through said rotor housing around said exhaust port and terminating in the other of said end housings, said housings further having a second pass coolant passage connected to said first pass coolant passage in said other end housing and extending axially through said rotor housing around said spark plug and terminating in said one end housing, said housings further having a bypass coolant passage originating at one end in said other end housing and extending axially through said rotor housing and around said intake ports in said end housings and connected at the opposite end to said pump inlet in said one end housing, a radiator having an inlet connected to said second pass coolant passage at said one end housing and having an outlet connected to said pump inlet at said one end housing, a heater having an inlet connected to said second pass coolant passage at said one end housing and having an outlet connected to said bypass coolant passage at said other end housing, said one end housing and said rotor housing having a heater bypass passage connected at one end in said one end housing to said second pass coolant passage and connected at the opposite end to said bypass coolant passage in said rotor housing and thus to said pump inlet in said one end housing, and thermostatically controlled valve means in said one end housing for blocking coolant flow to said radiator and permitting fluid flow to said heater bypass passage below a predetermined coolant temperature and, alternatively, permitting coolant flow to said radiator and blocking flow to said heater bypass passage above said predetermined temperature whereby when the engine is cool, coolant passes through said first pass coolant passage and then said second pass coolant passage and then said heater and then said bypass coolant passage to said pump inlet while coolant is also permitted to pass through said heater bypass passage to said pump inlet in parallel with coolant flow to said heater to prevent excessive pressures in said heater and when the engine has sufficiently warmed up, coolant passes first through said first pass coolant passage and then said second pass coolant Passage and then said radiator to said pump inlet while coolant continues to flow through said heater and then through said bypass coolant passage to said pump inlet.
 3. A rotary combustion engine having a pair of end housings, a pair of rotor housings between said end housings and an intermediate housing between said rotor housings, a coolant pump having an inlet and an outlet in one of said end housings, said housings having first pass coolant passage means connected to said pump inlet in said one end housing and extending axially in a plurality of branches through said rotor housings and said intermediate housing in an intermediate heat region thereof where working chamber exhaust occurs and terminating in the other of said end housings, said housings further having second pass coolant passage means connected to said first pass coolant passage means in said other end housing and extending axially in a plurality of branches through said rotor housings and said intermediate housing in the hotest heat region thereof where working chamber combustion occurs and terminating in said one end housing, said housings further having bypass coolant passage means originating at one end in said other end housing and extending axially in a plurality of branches through said rotor housings and said intermediate housing in the coolest region thereof where working chamber intake occurs and connected at the opposite end to said pump inlet in said one end housing, a radiator having an inlet connected to said second pass coolant passage means at said one end housing and having an outlet connected to said pump inlet at said one end housing, a heater having an inlet connected to said second pass coolant passage means at said one end housing and having an outlet connected to said bypass coolant passage means at said other end housing, said one end housing and the one rotor housing closest to said one end housing having heater bypass passage means connected at one end in said one end housing to said second pass coolant passage means and connected at the opposite end to said bypass coolant passage means in said one rotor housing and thus to said pump inlet in said one end housing, a bleed passage connecting said first pass coolant passage means to said bypass coolant passage means in said other end housing, and thermostatically controlled valve means in said one end housing for blocking coolant flow to said radiator and permitting fluid flow to said heater bypass passage means below a predetermined coolant temperature and, alternatively, permitting coolant flow to said radiator and blocking flow to said heater bypass passage means above said predetermined temperature whereby when the engine is cool, coolant passes through said first pass coolant passage means and then said second pass coolant passage means and then said heater and then said bypass coolant passage means to said pump inlet while coolant is also permitted to pass through said heater bypass passage means to said pump inlet in parallel with coolant flow to said heater to prevent excessive pressures in said heater and when the engine has sufficiently warmed up, coolant passes first through said first pass coolant passage means and then said second pass coolant passage means and then said radiator to said pump inlet while coolant continues to flow through said heater and then through said bypass coolant passage means to said pump inlet. 